by Svetlana N. Brzev, Marjorie Greene, Ravi Sinha
This typical rural construction in central, southern, and northern India houses millions of people. It is cheap to construct using field stones and boulders, but extremely vulnerable in earthquakes because of its heavy roofs and poorly constructed walls. The load-bearing structure is a traditional timber frame system, known as ‘khan’. It is a complete frame with timber posts spanned at about 2.6 m. Thick stone walls (typical thickness 600 mm – 1.2 m) provide enclosure and partial support to the roof. Walls are either supported by strip footings of uncoursed rubble masonry or are without any footings at all. The roof structure consists of timber planks and joists. To help keep the interiors cooler during hot summer months (peak temperatures exceeding 40°C.), a 500-800 mm thick mud overlay covers the top the roof. This construction type is considered to be very vulnerable to earthquake effects. Many buildings of this type were damaged or collapsed in the 1993 Killari (Maharashtra) earthquake (M 6.4) with over 8,000 deaths.